1. Field of the Invention
The present invention relates to an image pickup apparatus, and particularly relates to an image pickup apparatus for use in an apparatus for printing out characters or figures drawn on a wall, such as a blackboard, a white board, a notice-board or the like.
2. Discussion of the Related Art and Problems to Be Solved
A known apparatus for printing out characters, figures, etc. drawn on a blackboard or the like onto paper, is a so-called electronic blackboard. The electronic blackboard uses a blackboard (or a whiteboard) having a scanning function so that characters, figures, etc. drawn on the blackboard can be printed out onto paper by means of an integrally provided thermal printer unit on the basis of scanning information. Besides, there is an apparatus in which an original document is disposed at a predetermined position in a manner similar to that of a copying machine and the original document is read out by a scanner so as to be printed out.
Despite the fact that there are such known apparatus for printing out characters and/or figures on a special blackboard having a scanning function and for printing out the contents of an original document mounted at a predetermined position, it has heretofore been impossible to reproduce characters, figures and/or spatial sketches drawn on an ordinary blackboard provided with no scanning function, or drawn on a wall, a board or the like provided at the outdoors, onto paper as information. That is, it is impossible to print out those drawings on paper.
To solve such difficulties, the applicant of this application has proposed a so-called image pickup and printing apparatus in which characters, figures or the like drawn on various walls such as ordinary blackboard or the like are made incident through a lens, an angle of view is determined while monitoring the incident image through a view finder, the image is scanned by a linear image sensor, and a printer is operated in response to an image signal obtained by the scanning so that the characters, figures, or the like comprising that image are printed out on paper.
Although the above-mentioned image pickup printing apparatus can pickup the image of characters, figures or the like drawn on a wall as they are or pick up the image while changing an angle of view by using a zoom lens, it has been impossible to pick up the image while changing the aspect ration of the image in order to pick up a specific part of the image.
To better solve this existing need, applicant has conceived an apparatus in which members for limiting the scope of an image to be picked-up are provided for the above-mentioned linear image sensor and the displacement of the members is adjustable so that it is possible to pick up only a specific portion of those characters, figures or the like, which comprise the image.
In the case of thus picking-up only a specific portion, it is preferable to magnify that portion of the image to be printed. As a method for magnifying the image, although it could be magnified by a zoom lens or the like, such a method is disadvantageous in view of its cost because it is necessary to use an expensive zoom lens.
It is therefore desired to magnify the image to be outputted through data processing.
In the case of magnifying an image by a known general image processing method, binary data are held in a memory and the data are expanded by bit processing. For example, a known method to convert three-bit data into four-bit data is illustrated by the use of a 4/3-times conversion table shown in FIG. 9.
In such known method, not only a memory for holding data is required, but the magnifying power of the apparatus is limited. Moreover, since a conversion pattern appears in the printing output, the resolution of the apparatus deteriorates.